Beachable boats have used retractable rudders for many years and there have been many variations of methods to retract the rudder.
Rudder assemblies commonly have the ability to;                1) Securely hold the rudder in a vertical or down position for use while the vessel is underway.        2) Securely hold the rudder in a retracted or up position for times when it is desirable to have the rudder in the retracted position.        3) Break free of the vertical or down position when the rudder strikes a submerged object of the lake/ocean bottom without causing damage to the rudder assembly.        4) Raise or lower the rudder to the desired positions using one of a combination of a variety of devices including ropes, levers, cams, and springs.        
One problem with the existing rudder assemblies is that the rudder is still standing proud and is vulnerable to damage when it is retracted.                1) U.S. Pat. No. 6,739,276 describes a mechanism for retracting the rudder, but the rudder is always vulnerable in all of the positions.        2) U.S. Pat. No. 6,684,804 describes a design that is not vulnerable because it is flexible, but it does not have good authority to turn the boat and the rudder adds dimension to the boat.        3) U.S. Pat. No. 5,713,295 describes a rudder that is not vulnerable, but it would not have good authority to turn the boat.        4) U.S. Pat. No. 4,556,006 describes a retracting system but the rudder is vulnerable in all positions.        